Method of producing skin-covered pad for seat

ABSTRACT

A method of producing a skin-covered pad for a seat, which includes (a) preparing a lower mold which has a cavity formed therein; (b) putting a bag-shaped outer skin member into the cavity, the outer skin member including an innermost foamed layer which includes first and second parts which are exposed to the interior of the bag-shaped outer skin member, the first and second parts being wettable and non-wettable with respect to a given liquid material for foamed plastic; (c) pouring the liquid material into the bag-shaped outer skin member held in the lower mold, so that the innermost layer of the outer skin member is in contact with the liquid material for foamed plastic; and (d) putting an upper mold on the lower mold to close the cavity.

This application is a division, of application Ser. No. 07/200,633,filed May 26, 1988 now U.S. Pat. No. 4,927,694.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates in general to a method of producing askin-covered pad of a seat, and more particularly to a method ofproducing a skin-covered pad which has decorative ridges or projectionsformed on a front face thereof.

2. Description of the Prior Art

Hitherto, in the field of seat manufacturing, a so-called "skin-coveredpad" has been widely used as a cushion member of a seat cushion and/or aseatback. The skin-covered pad is arranged on the seat structure withits front face exposed to the outside. Usually, the skin-covered pad isproduced by pouring a liquid material for foamed polyurethane or thelike into a bag-shaped outer skin member held in a mold, and thereafter,curing the same in a suitable condition.

In order to improve the sitting comfort and the external appearance,some of the skin-covered pads are provided at their front faces with aplurality of decorative ridges or projections.

One of the methods for producing such ridges is taught by JapanesePatent First Provisional Publication No. 60-160990. In this method, thedecorative ridges are previously provided to the bag-shaped outer skinmember before the skin member is subjected to the molding of thepolyurethane foam. That is, the bag-shaped outer skin member with theridges is put into a mold, and thereafter, a liquid material for foamedpolyurethane is poured into the bag-shaped skin member held in the moldand cured in a known manner. In order to properly hold the skin membertherein, the mold has at its cavity bottom a corresponding number ofgrooves or recesses for engagement with the ridges of the skin member.

However, providing the ridges to the skin member prior to the urethanemolding increases the number of production steps of the skin-coveredpad. Furthermore, proper positioning of the skin member to the mold isdifficult or at least troublesome because of need of the properengagement between the ridges of the skin member and the grooves of themold. In fact, if the urethane molding is carried out with the ridges ofthe skin member mismatched with the corresponding grooves of the mold,an inferior product is inevitably produced.

Furthermore, in the above-mentioned method, a new mold becomes necessaryeach time design changing of the skin-covered pad is required. Thiscauses increase in cost of products.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a methodof providing a skin-covered pad having decorative ridges or projectionsformed thereon, which method is free of the above-mentioned drawbacks.

According to the present invention, there is provided an improved methodof producing a skin-covered pad for a seat. The method comprises (a)preparing a lower mold which has a cavity formed therein; (b) putting abag-shaped outer skin member into the cavity, the outer skin memberincluding an innermost foamed layer which consists of first and secondparts which are exposed to the interior of the bag-shaped outer skinmember, the first and second parts being wettable and non-wettable withrespect to a given liquid material for foamed plastic; (c) pouring theliquid material into the bag-shaped outer skin member held in the lowermold, so that the innermost layer of the outer skin member is in contactwith the liquid material for foamed plastic; and (d) putting an uppermold on the lower mold to close the cavity.

According to the present invention, there is further provided askin-covered pad for a seat. The skin-covered pad comprises a basestructure of foamed plastic; and an outer skin member which covers thebase structure, the outer skin member including an innermost foamedlayer which consists of first and second parts which are exposed to thebase structure, the first and second parts being wettable andnon-wettable with respect to a liquid material of the base structure.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the present invention will becomeapparent from the following description when taken in conjunction withthe accompanying drawings, in which:

FIG. 1 is a partically cut perspective view of a lower mold used in amethod according to the present invention, with a bag-shaped outer skinmember properly set in the mold;

FIGS. 2a, 2b and 2c are views of the part indicated by an arrow II inFIG. 1, showing various conditions of the part during molding ofurethane foam; and

FIG. 3 is a perspective view of a skin-covered pad produced by themethod of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following, a method according to the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 shows a lower mold 1 which is used in the method according to theinvention.

The lower mold 1 has a cavity formed therein which comprises laterallyspaced two deeper rounded portions 1a and a shallower flat portion 1bwhich is arranged between the deeper portions la, as shown. That is, thecavity of the lower mold is shaped to match with the contour of abacket-type seat cushion.

In the following, the steps for producing the skin-covered pad 10 (seeFIG. 2) will be described.

First, a bag-shaped outer skin member 2 is prepared. The skin member 2is shaped to match with the shape of the cavity of the lower mold 1 andthus comprises generally three parts 2a, 2b and 2a, which are stitchedto one another to constitute a bag-shaped structure. Each part is of alayered structure which comprises an outer skin 3 of knitted cloth, anon-wettable backing sheet 4 lined on the outer skin 3 and a wettablewadding 5 lined on the backing sheet 4. The wettable wadding 5 isconstructed of an open-cell polyurethane foam which is wettable to orintimate with a liquid material of polyurethane foam. (The "wettablewadding" is thus to be understood as a wadding which can be permeatedwith the liquid material.) As is shown in the drawings, two parallelstrap members 6 are arranged in the wettable wadding 5 of the middlepart 2b of the bag-shaped skin member 2. The strap members 6 areconstructed of a non-wettable material, such as a closed-cellpolyurethane, a polyurethane foam with baked outer surface or the like.Each strap member 6 is put in an elongate cut formed in the wettablewadding 5 and bonded to the wadding 5 through a suitable adhesive, as isseen from FIG. 2a. If desired, the bonding may be made through a highfrequency welding technique.

The bag-shaped outer skin member 2 having the above-mentionedconstruction is properly set in the lower mold 1. Then, a liquidmaterial for polyurethane foam is poured into the skin member 2 held inthe lower mold 1 and thereafter, an upper mold (not shown) is put on thelower mold 1 to close the cavity. Thus, thereafter, the urethanematerial is cured within the enclosed cavity. During this curing, as isseen from FIG. 2b, the non-wettable strap members 6 are compressedconsiderably by foaming pressure generated during the curing therebyreducing its thickness. While, the wettable wadding 5 does not show anotable reduction in thickness because it can impregnate the urethanematerial.

After the urethane material is hardened to a sufficient level, the uppermold is dismantled from the lower mold 1 and then a product, viz., theskin-covered pad 8, is removed from the lower mold 1. Upon this, due toremoval of the lower mold 1 against which the compressed non-wettablestrap members 6 have been pressed, the members 6 are expanded outwardlyas is seen from FIG. 2c thereby forming two parallel ridge portions 9 onthe front surface of the skin-covered pad 8.

Since the decorative ridge portions 9 of the skin-covered pad 8 areproduced automatically at the time when the urethane molding iscompleted, the production effeciency of the pad 8 is considerablyincreased. Furthermore, since the number and the shape of the ridgeportions 9 on the product 8 can be easily changed by modifying thestructure of the middle part 2b of the bag-shaped outer skin member 2,there is no need of preparing respective molds for the products havingdifferent ridge portions.

What is claimed is:
 1. A method of producing a skin-covered pad for aseat, comprising:(a) preparing a lower mold which has a cavity formedtherein; (b) placing a bag-shaped outer skin member into said cavity,said bag-shaped outer skin member including an innermost layer which hasfirst and second portions being wettable and non-wettable, respectively,by a foamable liquid material; (c) pouring said foamable liquid materialinto said bag-shaped outer skin member placed in said cavity so thatsaid innermost layer of said bag-shaped outer skin member is in contactwith said foamable liquid material; (d) placing an upper mold on saidlower mold to close said cavity; (e) foaming and curing said foamableliquid, wherein during said foaming said non-wettable second portion iscompressed relative to said wettable first portion via foaming pressuregenerated during said foaming; (f) dismantling said upper mold from saidlower mold upon sufficient hardening of said foamable material; and (g)removing a product formed of said foamable material from said lowermold, wherein upon removal said non-wettable second portion thenprojects outward relative to said wettable first portion due to theremoval of the lower mold against which said second portion wascompressed in step (e).
 2. A method as claimed in claim 1, wherein saidinnermost layer comprises a polyurethane foam sheet.
 3. A method asclaimed in claim 2, wherein said first portion of said innermost layercomprises an open-cell polyurethane foam, and said second portion ofsaid innermost layer comprises a closed-cell polyurethane foam.
 4. Amethod as claimed in claim 2, wherein said first portion of saidinnermost layer comprises an open-cell polyurethane foam, and saidsecond portion of said innermost layer comprises an open-cellpolyurethane foam having a baked outer surface.
 5. A method as claimedin claim 1, wherein said foamable liquid material is a foamablepolyurethane.
 6. A method as claimed in claim 1, wherein said bag-shapedouter skin member is of a layered structure comprising an outer layer, anon-wettable backing sheet lined on said outer layer with said innermostlayer lined on said backing sheet.
 7. A method as claimed in claim 6,wherein aid outer layer comprises knitted cloth.
 8. A method as claimedin claim 6, wherein said innermost layer comprises polyurethane foam. 9.A method as claimed in claim 1, wherein said first and second portionsare bonded by an adhesive.
 10. A method as claimed in claim 1, whereinsaid first and second portions are bonded by high frequency welding. 11.A method as claimed in claim 1, wherein said bag-shaped outer skinmember comprises three parts which are stitched to one another.